1. Field of the Invention
This invention relates in general to light receiving devices utilized in optical communications and light measurement equipment, and relates in particular to light receiving devices containing light receiving elements and ideal for precision mounting on circuit substrates.
2. Description of Related Art
The light receiver device is indispensable for applications such as in optical fiber communications equipment.
In many cases in the related art, light receiver devices are discretely (individually) mounted as a device package. In recent years however, due to factors such as the integration of optical circuit components, light receiver elements are capable of being mounted on optical waveguide substrates. Further, array type light receiving devices are being developed having numerous light receiving elements formed in an array configuration on the circuit substrate to use the devices for parallel optical transmission.
In light receiving devices of the related art, an optical fiber may for instance be placed in a groove formed on the circuit substrate with a reflector formed at the end of the groove. The beam of light from the optical fiber in the groove is reflected upwards by this reflector. Silicon substrates are generally used since they permit a V groove to be made in the circuit substrate with high precision by etching.
The light receiving element is mounted above this reflector, with its light sensitive surface facing downwards. The light receiving element can thus receive the light sent from the reflector and allow the light to be converted to electrical signals and extracted externally. The light receiving element has an anode and a cathode. These electrodes each have a connecting section to a corresponding surface on the substrate. These electrodes (anode and cathode) are connected by solder to the pad formed on the substrate.
However in the structure of the light receiving device of the related art, about one half of the light receiving element is on the lower surface of the groove so that the electrode cannot be positioned directly below or in the vicinity the light receiving element. This makes it necessary to make connections with the substrate at locations where no V groove is formed.
Trying to slant the electrode versus the light receiving element to make connections, does not allow the electrode to be mounted securely. Even if the self-attachment method is used by means of a solder bump, the solder bump is only present at two locations and since the position is tilted, ample self-adjustment cannot be achieved so high precision mounting is difficult.